Relevancy over the long term, which provides a compounding growth component

Quality management teams that will act in the best interest of shareholders

Favorable three-year investment horizon

The Fund strives to outperform the Russell Mid Cap Index over the long-run on a risk-adjusted basis with a high active share. The Fund attempts to shield investors from losses during bear markets.

Risks

The Fund’s share price may change daily based on the value of its security holdings.
Stock markets can be volatile, and stock values fluctuate in response to the asset
levels of individual companies and in response to general U.S. and international
market and economic conditions. Security holdings in the fund can vary significantly
from broad market indexes.

The Fund invests in the stocks of small and mid-cap companies, which are generally
riskier than larger companies, and the Fund’s share price may be more volatile than
funds that invest in larger companies.

Institutional Shares
Institutional Shares are generally for institutional investors and have a minimum
investment of $100,000. Institutional Shares are available to investors who invest
directly in the Fund as well as those who invest through certain intermediaries.
The minimum initial investment may be waived for group retirement plans. Please
see the prospectus for more details.

Investor Shares
Investor Shares are generally for individual investors have a minimum investment
of $2,000, which may be reduced to $500 for IRAs and certain custodial accounts.
Please see the prospectus for more details.

Avg. Weighted Mkt. Cap ($Bin)
The average capitalization of all stocks in the portfolio, weighted by each holding's
size in the portfolio. Capitalization, or market value of an entire company, is
calculated by multiplying the number of shares outstanding by the price per share.

P/E Ratio
A ratio of a stock's current price to its per-share earnings over the past 12 months
(or "trailing" 12 months). This gives us an idea of how "expensive" a stock may
be. For a fund, the price/earnings ratio is the weighted average P/E ratio of the
stocks it holds.

Alpha
A coefficient measuring risk-adjusted performance, considering the risk due to the
specific security, rather than the overall market. A large alpha indicates that
the stock or mutual fund has performed better than would be predicted, given its
beta.

Beta
A measurement of a fund's trailing 36-month returns in relation with the market
as a whole. A beta of 1 means that the share price moves exactly inline with the
market. A beta over 1 suggests that the share price will typically be more volatile
than the market, and conversely, a beta below 1 indicates that the share price will
typically be less volatile than the market.

Sharpe Ratio
A ratio used to measure risk-adjusted performance. It is calculated by subtracting
the risk-free rate from the rate of return for a portfolio and dividing the result
by the standard deviation of the portfolio returns.

As described in the Fund's current prospectus dated May 1, 2018, Parnassus Investments has contractually agreed to reduce its investment advisory fee to the extent necessary to limit total operating expenses to 0.99% of net assets for the Parnassus Mid Cap Fund—Investor Shares. This agreement will not be terminated prior to May 1, 2019, and may be continued indefinitely by the investment adviser on a year-to-year basis. The net expense ratio is what investors pay.

The Russell Midcap Index is a widely recognized index of common stock prices. An
individual cannot invest directly in an index. An index reflects no deductions for
fees, expenses or taxes, but mutual fund returns do.

The Morningstar Rating™ for funds, or "star rating", is calculated for managed products (including mutual funds,
variable annuity and variable life subaccounts, exchange-traded funds, closed-end funds, and separate accounts) with
at least a three-year history. Exchange-traded funds and open-ended mutual funds are considered a single population
for comparative purposes. It is calculated based on a Morningstar Risk-Adjusted Return measure that accounts for
variation in a managed product's monthly excess performance, placing more emphasis on downward variations and
rewarding consistent performance. The top 10% of products in each product category receive 5 stars, the next 22.5%
receive 4 stars, the next 35% receive 3 stars, the next 22.5% receive 2 stars, and the bottom 10% receive 1 star. The
Overall Morningstar Rating for a managed product is derived from a weighted average of the performance figures
associated with its three-, five-, and 10-year (if applicable) Morningstar Rating metrics. The weights are: 100% threeyear
rating for 36-59 months of total returns, 60% five-year rating/40% three-year rating for 60-119 months of total
returns, and 50% 10-year rating/30% five-year rating/20% three-year rating for 120 or more months of total returns.
While the 10-year overall star rating formula seems to give the most weight to the 10-year period, the most recent
three-year period actually has the greatest impact because it is included in all three rating periods. Parnassus Mid Cap
Fund was rated against the following numbers of Mid Cap Blend Funds over the following time periods: 371 funds in
the last three years, 334 funds in the last five years, and 230 funds in the last ten years. Past performance is no
guarantee of future results. Morningstar Rating is for the Investor class only; other classes may have different
performance characteristics.

Before investing, an investor should carefully consider the investment objectives,
risks, charges and expenses of a fund and should carefully read the prospectus or summary prospectus, which contains this and other information and can be found in our Forms and Documents
section. Investment return and principal value will fluctuate so that an investor’s
shares, when redeemed, may be worth more or less than their original principal cost,
and you could lose money.

The Parnassus Funds are underwritten and distributed by Parnassus Funds Distributor,
a subsidiary of Parnassus Investments and a
FINRA member.